Strut bar fasteners

[bpaynebearhawk]

Hi,

I am preparing to match drill my wing strut attach bars at the main spar splice plate. I am planning to drill under size and then ream to get a nice fit.
I plan to order the AN-4 fasteners from Aircraft Spruce, but I don't know exactly what should be used.

1) Where should flat washers be used? only under nut? none at all? (this affects the length)
2) What type lock nuts should be used? nylock? (elastic stop nuts)? safety wired castle nut?

Thanks,
Bill

[btdobie]

I haven't gotten to this point yet, but it occurs to me that you may want bolts longer than the final length for match drilling so the shank of the bolt extends all the way through. That may help keep things aligned easier.

[PaulSA]

Washer only needed under the nut. Nylock is what you want - castle nuts are used where there is rotation. Final fitting should have 1-3 threads showing when torqued. You can adjust by using up to 3 washers. Any more and you should go down one size on the bolt.

Wire locking is not used on castle nuts - you should use split pins. Wire locking is used on the heads of bolts threaded into structure where there is no nut or nutplate to lock it.